1. Field of the Invention
The present invention relates especially to the pursuit of a water sport, and most particularly to the water sport technique which enables a person to glide over water with the aid of a board.
This board, called a "sailboard" when the propulsive force is provided by wind pressure, and called a "surfboard" when the propulsion is provided solely by wave thrust, thus enables a person standing upright on it to execute manoeuvres on water.
2. History of the Related Art
The manner in which this water sport is practiced has undergone very considerable development in recent years. A sailboard conventionally consists of a float (or board) on which rigging - in the form of a mast - is articulated, allowing the setting of a sail which the user or "windsurfer", who stands on the float, holds in check and keeps in position by means of a bow which is called a "wishbone", the sail profile being delineated by battens. One or more fins are mounted beneath the float, in a manner such that they can be moved and/or adjusted, so as to reduce the drift of the board to leeward. The success of these sailboards has resulted in the appearance, on the market, of new models that exploit the very latest industrial technology, especially in order to improve the speed. In this regard, the shape, the hull underbody, the size and the weight are taken into consideration in order to offer the best guarantees aimed at reducing the resistance to the forward movement of the board over the water. Technical improvements have likewise been applied to the various elements of a board (the mounting of the mast and fin on rails extending over a portion of the length, the fixing of the mast to the float, the fixing of the wishbone to the mast, the provision of mast length adjustability, etc . . . ), the object being to augment the propulsive effect produced by the wind in the sail and thus to increase the propulsive force that enables the board to move over the water. Since the speed of a sailboard is proportional to the force propelling it, and inversely proportional to the resistance opposing forward movement, it will be understood that the abovementioned technical improvements have more particularly contributed to improving the speed of these boards.
There are boards of the "wave" type, on which the profile of the float undersurface has a convex curvature, and there are "speed" boards, on which the undersurface profile approximates to a straight line. It is obvious that the user will select the appropriate board according to the state of the water surface, and will for example select a speed board if the water is very smooth. This makes it necessary to own several boards or similar vehicles, which entails considerable expense, as well as transport problems. Should a user make do with owning only one board, its efficiency will be very poor when it has to be used under water surface conditions other than those for which it was designed.
In order to remedy these disadvantages, consideration has already been given to making a relatively short slanting slot in the rear of the float, the compliance being controlled solely by a spring or a "silentbloc". The deformation of this board corresponds only inaccurately to the loads imposed on it, since any deformation is distributed over too short a portion of its length.
This board, so to say, is never wholly suited to the essential conditions, namely the weight of the windsurfer, the "hardness" of the water surface, the wavelet height, etc. . . .
The refinements which are the object of the present invention are aimed at remedying these disadvantages, and at facilitating the production of a vehicle which, while of the type specified earlier in this document, satisfies the requirements of the technique under consideration, and does so more effectively than has previously been the case.